Secure communications system for collaborative computing

ABSTRACT

A distributed collaborative computer system is provided that comprises a plurality of server computers interconnected via a high-speed link. Client computers can connect to any available server computer and start or join a conference hosted on either the server computer to which the client computer is connected or any other server in the system. As a result, the system and method of the present invention is easily scalable to support an arbitrary number of participants to a conference by merely adding the appropriate number of server computers to the system. In addition, by replicating the conference information on more than one server computer, the single point of failure limitation is eliminated. In fact, if a server hosting or participating in a conference malfunctions, the failure is detected by other server computers and the client computer is able to reconnect to the conference through a new server computer.

CROSS-REFERENCE TO CD-ROM APPENDIX

An Appendix containing a computer program listing is submitted on acompact disk, which is herein incorporated by reference in its entirety.The total number of compact discs including duplicates is two. AppendixA, which is part of the present specification, contains a list of thefiles contained on the compact disk. These listings contain materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the patent and trademarkoffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to computer networks and, moreparticularly, to collaborative computing over a computer network.

2. Description of the Related Art

Traditional collaborative computing tools allow computer users atdifferent locations to communicate via a computer network and sharedocuments or applications stored and/or executed on one the user'scomputers. While both peer-to-peer and client-server communicationmodels have been used in the past, web-based collaborative toolsgenerally employ a client-server model.

For examples client-server application sharing (also discussed in thecontext of “distributed-computing”) is described in U.S. Pat. No.5,434,852 “Distributed Processing Architecture for Control of Broadbandand Narrowband Communication Networks;” U.S. Pat. No. 5,887,170 “Systemfor Classifying and Sending Selective Requests . . . ;” and U.S. Pat.No. 6,038,593 “Remote Application Control for Low Bandwidth ApplicationSharing,” all incorporated herein by reference in their entireties.Other group communication techniques are described by Ulrick Hall andFranz J. Hauck, “Promondia: A Java-Based Framework for Real-time GroupCommunication in the Web,” Proceedings of Sixth International World WideWeb Conference (Apr. 7-11, 1997); Lane Boyd, “Taking Collaboration IntoOrbit,” Computer Graphics World, Vol. 21, No. 9, p. 36 (September 1998);and Eric Ly, “Distributed Java Applets for Project Management on theWeb,” IEEE Internet Computing Online, Vol. 1, No. 3 (May/June 1997), allincorporated herein by reference in their entireties.

International Telecommunications Union (ITU) Standard T.120 is a familyof open standards that provides both communications and applicationsprotocols to support real-time multipoint data communications forcollaboration and conferencing, among other uses. This standard isoutlined in A Primer on the T.120 Series Standard by DataBeam Corp. (May14, 1997), incorporated herein by reference in its entirety.

FIG. 1A is a block diagram illustrating the communication scheme usedfor an exemplary traditional collaborative computer system 100. In FIG.1A, client computers 110 n (where n=A, B, C . . . ) can connect toserver computers 120 n over a global-area computer network 130 (e.g.,the Internet). As used herein, the numeral n appended to a referencenumber does not imply any correspondence among elements having differentnumerals (e.g., client computer 110A bears no relationship to servercomputer 120A). FIG. 1B is a block diagram illustrating the actualcommunications channels established between client computers 110 n andserver computers 120 n to set up two conferences between users of clientcomputers 110A and 110B on the one end and 110C and 110D on the other.As is readily apparent from inspection of FIG. 1B, each conference ishandled by a single server computer 120 n. This model performssatisfactorily for conferences having a small number of participants andconferences that do not require fault tolerance. However, as the numberof participants in a conference increases, the computing power of servercomputer 120 n becomes a bottleneck. Furthermore, if the particularserver computer 120 n that is handling a conference malfunctions, theentire conference is disrupted (i.e., server computer 120 n represents asingle point of failure for the entire system handling that conference).Accordingly, there is a need for an improved collaborative computingsystem.

BRIEF SUMMARY OF THE INVENTION

The system and method of the present invention provide a distributedcollaborative computer system that is scalable to handle an arbitrarynumber of conference participants and eliminates the server as thesingle point of failure in the system. This is accomplished by providinga plurality of server computers interconnected via one or morehigh-speed links. Client computers can connect to any available servercomputer and start or join a conference hosted on either the servercomputer to which the client computer is connected or any other serverin the system. As a result, the system and method of the presentinvention is easily scalable to support an arbitrary number ofparticipants to a conference by merely adding the appropriate number ofserver computers to the system. In addition, by replicating theconference information on more than one server computer, the system andmethod of the present invention eliminate the single point of failurelimitation of prior art systems. In fact, if a server hosting orparticipating in a conference malfunctions, the failure is detected byother server computers and the client computer is able to reconnect tothe conference through a new server computer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood and its numerousfeatures and advantages made apparent to those skilled in the art byreferencing the accompanying drawings.

FIG. 1A is a block diagram of a prior art collaborative computer system.

FIG. 1B is a block diagram illustrating the connections establishedbetween the client and server computer of FIG. 1A during twoconferences.

FIG. 2A is a block diagram of a distributed collaborative computersystems, in accordance with some embodiments of the invention.

FIG. 2B is a block diagram illustrating the connections establishedbetween the client and server computers of FIG. 2A during a conference.

FIG. 3 is a block diagram of the software components of a distributedcollaborative computer system, in accordance with some embodiments ofthe invention.

FIGS. 4A, 4B, and 4C are flow diagrams illustrating a start/joinconference operation on the distributed collaborative computer system ofFIG. 3.

FIG. 5 is a flow diagram of the operation of the log server of FIG. 3.

FIG. 6 is a flow diagram of the operation of the license server of FIG.3.

FIG. 7 is a flow diagram of the operation of an App server of FIG. 3.

FIGS. 8, 9, 10, and 11 are flow diagrams illustrating the operation ofthe meeting manager of FIG. 3.

FIG. 12 is a block diagram illustrating the software components of theclient and server computers of FIGS. 2A and 2B.

FIGS. 13A, 13B, and 13C are flow diagrams illustrating the operation ofthe CB server and App servers of FIG. 3.

FIG. 14 is a block diagram illustrating the communication channelsestablished between two client computers of FIG. 3 during an on-lineconference, in accordance with an embodiment of the invention.

FIG. 15 is a flow diagram of an operation for transmitting data betweenthe client computers of FIG. 14.

FIGS. 16A and 16B are flow diagram illustrating a skip page operationused to control transmission of pages between a presenter's clientcomputer and other participants' client computers, in accordance withsome embodiments of the invention.

FIG. 17 is a flow diagram of a client browser operation, in accordancewith some embodiment of the invention.

FIGS. 18A, 18B, 18C1-3, 19A, 19B, 20A, 20B and 20C are views of webpages displayed by client browser of FIG. 3 during operation of thedistributed collaborative computer system of FIG. 3.

The use of the same reference symbols in different drawings indicatessimilar or identical items.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2A illustrates a distributed collaborative computing system 200, inaccordance to some embodiments of the invention. Client computers 210 n(where n=A, B, C . . . ) are connected to server computers 220 n viaglobal-area computer network 130. Unlike in the prior art system ofFIGS. 1A and 1B, each client computer 210 n can connect to any servercomputer 220 n. Server computers 220 n are in turn connected through ahigh-speed link 230. High speed link 230 allows faster throughput and ahigher level of security than global-area network 130. For example, insome embodiments high-speed link 130 is a dedicated T1 or T3 or opticalcarrier-class link, such as one employing the well-known SONET standardand OC-48 or OC-192 framing. One of ordinary skill in the art willreadily recognize that many other equivalent high-speed networkstandards, including non-optical standards, may be employed to create ahigh bandwidth link.

FIG. 2B illustrates the connections established between client computers210 n and server computers 220 n to conduct a conference betweenparticipants seated at client computers 210A and 210D, respectively.First, client computer 210A (whose user will host the conference)establishes a connection 225A to server computer 220A over global-areanetwork 130. Server computer 220A, in turn, is connected to servercomputer 220B via high-speed link 230. Finally, client computer 210D,whose user will join the conference hosted by the user of clientcomputer 210A, establishes a connection 225B to server computer 220Bover global-area network 130. As a result, information transmitted fromclient computer 210A travels through connection 225A, high-speed link230 and connection 225B to reach client computer 210D. Similarly,information transmitted from client computer 210D travels throughconnection 225B, high-speed link 230 and connection 225A to reach clientcomputer 210A. Since high-speed link 230 is several orders of magnitudefaster than connections 225A and 225B, the delay introduced byhigh-speed link 230 is transparent to the users of client computers 210Aand 210B.

FIG. 3 is a block diagram of the software components of a distributedcollaborative computer system 300, in accordance with some embodimentsof the invention.

Distributed collaborative computer system 300 includes meeting zones 310n (where n=A, B, C), client browser 320, web zone 330 and centraloperation database 350. Client browser 320 is a web browser programexecuted on one of client computers 210 n (FIGS. 2A and 2B). Clientbrowser 320 first connects to web zone 330 to request starting orjoining a conference. Web zone 330, in turn, verifies the user andconference information and updates central operation database 340accordingly. Once web zone 330 has verified that the user is authorizedto start/join a conference, client browser 320 connects to one ofmeeting zones 310 n to access the conference. Meeting zone 310 n, inturn, connects client browser 320 to the desired conference and updatescentral operation database 340 accordingly.

Web zone 330 includes a web server 335 that maintains a website to allowusers to access distributed collaborative computer system 300 and a webdatabase 337 that stores web usage and administrative information aboutusers of distributed collaborative computer system 300. The informationstored in web database 337 is periodically synchronized and/orreplicated with the information stored in central operation database 340to ensure data consistency.

Each meeting zone 310 n, in turn, includes a meeting manager 350, a pingserver 355, a license manager 360, a meeting database 365, a log server370, collaboration (CB) servers 386 n, and application (App) servers 390n. Furthermore, each meeting zone 310 n also includes a process manager(PM) 311. Process manager 311 is the controlling process for all logicalservers running on a physical server within the meeting zone. PM 311thus monitors the health of all logical servers and processes running onthe physical server and spawns replacement processes on failure.Alternatively, PM 311 can start new processes on command from remoteaccess service (RAS) 312.

In one embodiment of the present invention, a single instance of meetingzone 310A is implemented on one physical server (i.e., one machine).

In some embodiments, each meeting zone is implemented on a singlephysical server. One of ordinary skill will readily appreciate, however,that multiple physical servers could also be used either as hot or warmstandby units for redundancy or to spread the logical server loadingacross multiple machines, each with its own PM. Alternatively, severalmeeting zones could be implemented on one physical server, either havingtheir own PM, or sharing a single PM.

PM 311 spawns each logical server (e.g., CB servers 380A, 380B, 380C;App server 390A, 390B, 390C; meeting manager 350, ping server 35, logserver 370, and license manager 360) as directed by a startupconfiguration file or operator command through RAS 312. RAS 312 is, insome embodiments, a real-time messaging service such as TIBCORendezvous, available from TIBCO Software, Inc. of Palo Alto, Calif.

Each logical server has its . . . own communications and control moduleknown as a zone manager (ZM). Conceptually, each ZM 313 is functionallysimilar although one of ordinary skill in the art will appreciate thatimplementation optimizations may allow for reduced functionality in someinstances of ZM 313.

Meeting manager 350 also possesses a special zone manager 314, sodesignated because it also acts as a gatekeeper (GK) for the entitymeeting zone 310. The GK maintains a subset of the state of each logicalserver so that meeting manager 350 has immediately available thedetailed status of the entire meeting zone 310.

Each ZM, which is spawned (created) in direct correspondence to eachlogical server or autonomous process on a-given physical server machine,monitors the health and status of its corresponding logical server orprocess. All logical server communications with other logical serversand with the process manager 211 go through the ZM in each logicalserver and the PM.

The operational functions of PM 311, RAS 312, ZM 313, and ZM/GK 314 arediscussed in further detail below.

All ZMs report to a single “super ZM”, known as the gatekeeper or ZM/GK.Each ZM sends a subset of its corresponding logical server's state andtraffic capacity to the ZM/GK so that the GK is aware of the status ofall elements of the meeting zone. This enables the meeting manager toget coordinated zone state reports and therefore “know” the status ofthe entire meeting zone.

Zone status is important to the meeting manager (and thus to the overallhealth and efficiency of the zone) because the meeting manager usesZM/GK state reports to manage both the zone's overall quality of service(QoS) and the load balance across all active collaboration servers (CBs)in the zone.

QoS, in this context, refers to the zone's ability to respond to clientdata requests of all types (e.g., HTTP, application sharing, documentsharing, telephony, and so forth). In addition, QoS is an indirectindicator of latency to those requests, caused by high and possiblyunbalanced loading of the logical servers in the meeting zone. Forexample, in some embodiments of the present invention, a meeting managerfaced with a need to add more user participants to an in-progressmeeting must determine if an additional CB server must be spawned (i.e.,brought on-line) to keep overall CB server loading below a certainthreshold. This “intelligence” in the MM is implemented through the ZMsin each CB and the coordinating function of the ZM/GK reporting to theMM. The MM can thus decide if the pre-defined QoS for the specific userclient (perhaps determined by the time of day, the user's license, orthe type of service purchased by the user or some communication thereof,to name but a few examples), would be unobtainable without additional CBserver resources. If so, the meeting manager will request that theprocess manager spawn a new CB server.

Once client browser 320 has received authorization to start/join aconference, client browser 320 attempts to connect to ping servers 355in multiple meeting zones 310 n. Client browser 320 selects the firstping server to respond to the connection request and disconnects otherresponding ping servers 355. The selected ping server, in turn, forwardsthe request to start/join a conference to a meeting manager 350 in thesame meeting zone 310 n as the selected ping server 355. Meeting manager350, in turn, assigns a CB server 380 n to host/handle the conference.The selected CB server 380 n connects to client browser 320 and anyother CB servers 380 n handling the conference that the user wishes tostart/join. Thus, client browser 320 communicates with otherclient->browsers 3.20 via the selected CB server 380 n.

App servers 390 n are used by CB servers 380 n and client browsers 320to support services such as document view, file sharing, video, voiceover IP, telephony, polling, chat and application sharing. Collaborativesupport for these services are further described in the followingreferences, each incorporated herein by reference in its entirety:

“Instant Document Sharing,” co-pending and commonly-assigned Applicationfor a U.S. patent Ser. No. 09/442,424, filed Nov. 17, 1999.

“Instant Sharing of Documents in a Remote Server,” co-pending andcommonly-assigned Application for U.S. patent Ser. No. 09/471,938, filedDec. 23, 1999.

“Remote Document Serving,” co-pending and commonly-assigned Applicationfor a U.S. patent Ser. No. 09/591,377, filed Jun. 9, 2000.

“Instantaneous Remote Control of an Unattended Server,” co-pending andcommonly-assigned Application for a U.S. patent Ser. No. 09/515,684,files Feb. 29, 2000.

“Method for Creating Peer-to-Peer Connections Over an InterconnectedNetwork to Facilitate Conferencing Among Users,” co-pending andcommonly-assigned Application for a U.S. patent Ser. No. 08/609,025,filed on Feb. 29, 1996.

“Method for Establishing a Communication Connection Between Two or MoreUsers Via a Network of Interconnected Computers,” co-pending andcommonly-assigned Application for a U.S. patent Ser. No. 09/195,801,filed on May 12, 2000.

“Emulating a Persistent Connection Using HTTP,” co-pending andcommonly-assigned Application for a U.S. patent Ser. No. 09/449,011,filed on Nov. 24, 1999.

“Method of Transferring Data at Adjustable Levels of Priorities toProvide Optimum Response to User Demands,” U.S. Pat. No. 5,623,603.

“Method to Provide for Virtual Screen Overlay,” U.S. Pat. No. 5,577,188.

“Collaborative Web Browser,” U.S. Pat. No. 5,944,791.

Log server 370 communicates with meeting manager 350 via theirrespective ZMs 313 and 314 and stores information related to new usersjoining/leaving conferences and updates meeting database 365. Licensemanager 360 communicates with meeting manager 350 (again, through ZMs313 and 314) and polls meeting database 360 to ensure that the number ofusers authorized to join a meeting is not exceed.

Overall fault tolerance is ensured by providing process-level faultmonitoring by the ZM and correction (e.g., process replacement) by thePM. At the logical server level, the MM uses ZM/GK sate monitoring todetect logical server faults and PM commands to spawn replacements.Logical server state replication is also provided by the gatekeeper,using the meeting database. Finally, physical server fault tolerance isprovided by operator hardware and environmental status using acombination of manual and RAS monitoring and control methods well-knownin the art.

FIGS. 4A-4C are flow diagrams illustrating a start/join conferenceoperation 400 on distributed collaborative computer system 300 (FIG. 3).

First, in stage 402, client browser 320 connects to a web server 335. Ifthe connection is successful (stage 404), operation 400 proceeds tostage 406, otherwise stages 402 and 404 are repeated. In stage 406, theuser of client computer 320 logs on to web server 335. In stage 408, theinformation entered by the user in stage 406 is authenticated withinformation stored in web database 337. If the information entered bythe user cannot be authenticated, stages 406 and 408 may be repeateduntil the information entered by the user is successfully validated. Insome embodiments, client browser 320 is disconnected after apredetermined number of login attempts to prevent unauthorized access toweb server 335. As those skilled in the art are familiar with techniquesfor preventing/deterring unauthorized access to a website, thesetechniques are not further discussed herein.

Once the user has successfully logged on to web server 335, stage 410determines whether the user is requesting to start a new conference orjoin an existing conference. If the user is requesting to join a newconference, operation 400 proceeds to stage 412, otherwise operation 400proceeds to stage 450.

In stage 412, meeting parameters are extracted from meeting database 365through web database 337. In stage 414, a plug-in for client browser 320is launched on client computer 210 n (FIGS. 2A and 2B). The first timethe user of client browser 320 connects to web server 335, the plug-inis downloaded over global-area network 130 and installed on the clientcomputer 210 n. After the plug-in is installed on client computer 210 n,it can be re-used for subsequent conferences without the need fordownloading and reinstalling it. In some embodiments, multiple versionsof the plug-in are used over time: when a new version of the plug-inbecomes available on web server 335, the new plug-in is downloaded toclient computer 210 n and installed in place of the older version of theplug-in.

In stage 416, the meeting parameters are sent from meeting database 365(via web database 337) to client computer 210 n and operation 400proceeds to stage 418 (FIG. 4B).

In stage 418, client browser 320 attempts to connect to any availableping server 355. In stage 420, responses are received from one or moreping servers 355. In some embodiments, if no response is received withina predefined time limit, stages 418 and 420 are repeated until aresponse is received within either the original time limit or a newlydefined time limit. Client browser 320 selects the fastest ping server355 to respond to the connection request (stage 422) and disconnects thenon-selected ping servers 355 (stage 424). Client browser 320 then sendsa request to join a meeting to the selected ping server 355 (stage 426)and ping server 355 forwards the request to a meeting manager (MM) 350(stage 428) in the same meeting zone 310 n (FIG. 3) as ping server 355.

Upon receiving the request to join a meeting, meeting manager 350selects a collaboration (CB) server 380 n from a pool of available CBservers 380 n in the meeting zone 310 n (stage 430). In stage 432 (FIG.4C), the selected CB server 380 n queries other CB servers 380 n in allmeeting zones 310 n to ascertain which CB server 380 n is hosting themeeting to which the user of client browser 320 is attempting toconnect. Once client CB server 380 n locates the hosting CB server 380n, it connects to the hosting CB server 380 n (stage 434). Client CBserver 380 n then makes a local copy of the meeting data from hosting CBserver 380 n.

Stage 438 determines whether meeting manager 350 has received a meetingconfirmation from client CB server 380 n, in which case operation 400proceeds to stage 440. Otherwise stages 418-438 are repeated with a newclient CB server 380 n.

In stage 440, meeting manager 350 has received confirmation from CBserver 380 n that a connection has been successfully established withthe hosting CB server 380 n. The confirmation is then transmitted frommeeting manager 350 to ping server 355 and from ping server 355 toclient browser 320 (stage 442).

If the user requests starting a new meeting in stage 410, operation 400proceeds to stages 450-472. Stages 450-466 are analogous to stages414-430 and stages 468-472 are analogous to stages 438-442, except thatif stage 468 fails, operation 400 proceeds to stage 454 rather thanstage 418.

FIG. 5 is a flow diagram of the operation 500 of log server 370 of FIG.3. In operation 500, stage 510 determines whether a new log entry hasbeen posted and stage 520 updates meeting database 365 (FIG. 3).

FIG. 6 is a flow diagram of the operation 600 of license server 360 ofFIG. 3. First, stage 610 determines if a new user has requested joiningthe meeting, in which case operation 600 proceeds to stage 620.Otherwise, stage 610 is repeated. In stage 620, license manager 360compares the number of users in the meeting if the current user wereallowed to join the meeting to the user limit for the meeting. Stage 630then determines whether the user limit is exceed, in which case CBserver 380 n is notified (stage 640). Otherwise stages 610-630 arerepeated.

FIG. 7 is a flow diagram of the operation 700 of an application (App)server 390 n of FIG. 3. First, App server 390 n registers with meetingmanager 350 in the same meeting zone 310 n (FIG. 3) in stage 710.Meeting manager 350, in turn, allocates App server 390 n to a CB server380 n handling a given conference (stage 720). CB server 380 n, in turn,initializes App server 390 n with the necessary application datarequired for the conference (stage 730) and establishes a connection toApp server 390 n (stage 740) via ZMs 313. CB server 380 n notifies Appserver 390 n of meeting events (e.g., users joining/leaving the meetingor control passing from the host to another user) in stage 750. Finally,App server 390 n establishes a connection with client browser 320 via CBserver 380 n (stage 760) which allows users of client browsers 320 toaccess and interact with the application provided by App server 390 n.

FIGS. 8-11 are flow diagrams illustrating the operation of meetingmanager (MM) 350 for providing fault tolerance to distributedcollaborative computer system 300.

FIG. 8 illustrates CB server failure detection and recovery operation800. First, meeting manager 350 checks whether any CB servers 380 n inthe meeting manager's meeting zone 310 n have failed (stage 810). Avariety of techniques known in the art can be employed to detect failureof CB servers 380 n. For example, CB servers 380 n can periodicallytransmit a “heartbeat” message to meeting manager 350. If meetingmanager 350 does not receive a heartbeat message from a CB server 380 nwithin a predefined time limit, meeting manager 350 attempts to contactCB server 380 n and if no response is received from CB server 380 nwithin a predefined time limit, meeting manager 350 determines that CBserver 380 n has failed. Other failure detection techniques known in theart can be used to detect failure of a CB server 380 n in accordance oneor more embodiments of the present invention. Accordingly, the presentinvention is not limited to any particular failure detection technique.

In some embodiments of the present invention, meeting manager 350employs its zone manager (and meeting zone gatekeeper) (ZM/GK) 214 toexchange heartbeat (or analogous) messages with ZM 313 in each CB server380 n. When and if ZM/GK 314 detects a CB server (or other logicalserver failure) by noting a lack of heartbeats, for example, ZM/GK sendsa request to process manager (PM) 311 to restart the dead logicalserver.

PM 311 also monitors each ZM 313, including ZM/GK 314, to evaluate ZMhealth. Should PM 311 discover a failed or stopped ZM process, the PMwill restart (i.e., spawn a replacement for) the ZM.

In particular, if failure of a CB server 380 n is detected in stage 810,operation 800 proceeds to stage 820. Otherwise stage 810 is repeateduntil a failure is detected. Meeting manager 350, in turn, retrieves alist of meetings handled by failed CB server 380 n from meeting database365 (stage 820) and sends a request to process manager 311 to launch anew CB server 380 n (stage 830).

The newly-spawned (replacement) CB server recovers its state information(e.g., information describing its configuration, operating or quality ofservice [QoS] parameters, and/or current meeting data) from the localmeeting zone's gatekeeper. Typically, this is the ZM/GK 314 within zonemanager 350, but the gatekeeper function may alternately be provided byany designated ZM 313. Generally speaking, all local state in a logicalserver is preserved. However, if an application server goes down, theapplication state is lost. Only the meeting state is preserved in thiscase.

Stage 840 then determines if the new CB server 380 n has successfullycome on-line, in which case meeting manager 350 continues to monitor thestatus of CB servers 380 n (stage 810). Otherwise, stages 830-840 arerepeated until a new CB server 380 n successfully comes on-line.

FIG. 9 illustrates the application server failure detection and recoveryoperation 900. First, meeting manager 350 and CB servers 380 n (FIG. 3)check whether any App servers 390 n in the same meeting zone 310 n asmeeting manager 350 and CB servers 380 n have failed. As explainedabove, this can be accomplished using any failure detection techniqueknown in the art. In case CB server 380 n detects a failure of an Appserver 390 n before meeting manager 350, CB server 380 n notifiesprocess manager 311 through the zone manager 313 communication path. Insome embodiments, the zone managers communicate with each other and thedesignated ZM/GK 314 using the well-known TCP/IP protocol and simplemessages whose content and format are readily apparent to those ofordinary skill in the inter-process communication arts. In otherembodiments, the WebEx Transport Layer protocol is used.

The WebEx Transport Layer protocol (TP) is responsible for providingpoint-to-point connectivity between a WebEx client and the WebEx server.The TP layer will attempt to create direct TCP connections and use TCPto communicate between the client and server. For clients that sitbehind firewalls, particularly for those that are unable to createdirect TCP connections, the WebEx TP layer will automatically createvirtual sockets based upon HTTP. This enables the client to communicatewith the server through most firewalls.

Since the HTTP protocol functions on a Request/Response basis, it isalways the client that issues the Request command. Hence, in order toprovide a bidirectional communication channel, the client actively pollsthe server in order to fetch the data that may be sent from the serverto the client. The details of this implementation are available in theco-pending and commonly-assigned-Application for a U.S. patent Ser. No.09/449,011, filed on Nov. 24, 1999, “Emulating a Persistent ConfectionUsing HTTPI,” cited and incorporated above.

If a failure of App server 390 n is detected, operation 900 proceeds tostage 920. Otherwise stage 910 is repeated. In stage 920, meetingmanager 350 places any CB servers 380 n connected to failed App server390 n in a suspend state and receives a request for a new App server 390n from CB server 380 n in stage 930. Meeting manager 350 then requeststhat process manager 311 launch a new App server 390 n (stage 940).Process manager 311 launches the new App server 390 n and notifiesmeeting manager 350 (stage 950).

Once meeting manager 350 has received notification that the new Appserver 390 n has been launched, meeting manager 350 resumes (i.e.,removes from the suspend state) CB server 380 n and connects it to thenew App server 390 n (App server state is restored from a backup meetingmanager, through any of a number of standard and common means well-knownin the art.) Meeting manager continues to monitor the status of Appserver 390 n (stage 910). Note that all logical server-to-logical serverand logical server-to-PM communications employ ZMs 313 and 314.

FIG. 10 illustrates the license/log manager failure detection andrecovery operation 1000. First, meeting manager 350 checks whetherlicense manager 360 or log server 370 have failed, using similartechniques to the ones described above in reference to FIGS. 8 and 9. Ifa failure is detected, operation 1000 proceeds to stage 1020. Otherwise,stage 1010 is repeated until a failure is detected. Meeting manager 350,in turn, sends a request to process manager 311 to launch a new licensemanager 360 or log server 370 (stage 1020), as required. Stage 1030 thendetermines whether the new license manager 360 or log server 370 hassuccessfully come on-line, in which case meeting manager 350 continuesto monitor the status of license manager 360 and log server 370 (stage1010). Otherwise, stages 1030 and 1040 are repeated until a new licensemanager 360 or log server 370 has been successfully started.

Note that the reliable TP layer keeps all data and resends/reloads itinto the replacement license and/or log server as needed.

FIGS. 8-10 thus show how meeting manager 350 monitors the status ofother components in its meeting zone 310 n. However, to provide evenmore effective fault tolerance, the status of meeting manager 350 mustalso be monitored to prevent a single point of failure in the system.This is accomplished by providing both a primary and one or more standbymeeting managers 350 in each meeting zone 310 n. In addition, processmanager 311 is responsible for detecting failure of the primary meetingmanager 350 and transferring control to one of the backup meetingmanagers 350. Operability of the process manager, in turn, is guaranteedby a hardware time-out restart process.

FIG. 11 illustrates meeting manager failure detection and recoveryoperation 1100. In each meeting zone 310 n (referring to FIG. 3), thereis instantiated one primary meeting manager 350 and one or moresecondary meeting managers (not shown). Process manager 311 continuallychecks whether primary meeting manager 350 has failed (stage 1110),again using standard failure detection techniques. If a failure ofprimary meeting manager 350 is in fact detected, operation 1110 proceedsto stage 1120. Otherwise, stage 1110 is repeated.

In stage 1120, process manager 311 launches a new standby meetingmanager. The per-existing standby meeting managers, advised of thefailure of primary meeting manager by process manager 311, elect(through any of several well-known server election or promotionmechanisms) one of their own (step 1140) to take over as primary andbroadcast an election message (stage 1140). One of the standby meetingmanagers is thus selected as the new primary meeting manager 350 (stage1150). In the event only one standby MM is presently configured, theelection message stage 1140 is simply construed as a command to becomethe primary MM.

The standby meeting manager(s) 350, CB servers 380 n, App server 390 n,ping servers 355, license manager 360, and log server 370 in the samemeeting zone 310 n as new primary meeting manager 350 connect to newprimary meeting manager 350 (stage 1160) and register with it (stage1170) so that the new primary meeting manager can continue to monitorthe status of these servers. New primary meeting manager 350 recoversits server state (stage 1180) and receives reports from CB servers 380 non the status of any active conferences handled by CB servers 380 n(stage 1190). Finally, new primary meeting manager 350 recovers meetinginformation for all meetings handled in the meeting zone 310 n (stage1190). Process manager 311 monitors the status of new primary meetingmanager 350 (stage 1110).

CB server 380 n interfaces with client browser 320 through applicationprotocol entities (APEs) joined to agent sessions. FIG. 12 is a blockdiagram illustrating the software components of client computers 210 nand server computers 220 n (FIGS. 2A and 2B) involved in thecommunications between CB server 380 n and client browser 320. Inparticular, communications channels are established between transactionprocessing (TP) server 1250 and Application Resource Manager (ARM)server 1240 on server computer 220 n and TP client 1230 and ARM client1220 on client computer 210 n. Thus, conference manager 1260 and Appserver 390 n (both logically part of CB server 380 n) communicate withclient computer 210 n via the communication channels maintained by ARMserver 1240 and TP server 1250.

FIGS. 13A-13C are flow diagrams illustrating the operation 1300 of CBserver 380 n and App server 390 n to setup communications with clientbrowser 320 (FIG. 3). First, CB server 380 n creates an agent session(stage 1305). The agent session controls communications from clientcomputer 210 n to CB server 380 n and can launch new, additional datasessions if required. To communicate with CB server 380 n, clientcomputer 210 n, in turn, creates an APE (stage 1310) and joins the APEto the agent session (stage 1315). In stage 1316, CB server 380 n sendsa list of all existing session to the client computer 210 n; in stage1317, the client must chose whether to join all or only some sessions.If client computer 210 n joins all sessions, control passes to stage1320, shown in FIG. 13B. If not, stage 1318, the client joins onlyselected sessions before control passes to stage 1320.

Stage 1320 (FIG. 13B) determines whether the user of client computer 210n has elected to create a new session (e.g., to share an application),in which case operation 1300 proceeds to stage 1325. Otherwise,operation 1300 proceeds to stage 1360. Client computer 210 n APE thensends a message to the agent session APE of CB server 380 n requesting anew session (stage 1325). CB server 380 n, in turn, requests a newsession from App server 390 n (stage 1330) and App server 390 n createsthe new session for the conference (stage 1335). App server 390 n alsocreates a new APE and joins the new session to the new APE (stage 1340)CB server 380 n, in turn, sends the new session's ID to client computer210 n (stage 1345). Client computer 210 n launches an application (stage1350), creates a new APE for the application and joins the new APE tothe new session (stage 1355, referring to FIG. 13C).

Stage 1360 determines if a new client computer 210 n wants to join anexisting session, in which case operation 1300 proceeds to stage 1370.Otherwise, operation 1300 terminates. Client computer 210 n requestsjoining the session (stage 1370), concluding operation 1300.

FIG. 14 is a block-diagram illustrating the communication channelsestablished between client computers 210A and 210B during an on-lineconference, in accordance with an embodiment of the invention. Clientcomputer 210A connects to CB server 380B in meeting zone 310A via ARMserver 1240 and TP server 1250. In addition, CB server 380B establisheda high-speed real-time messaging link 1420 with CB server 380C inmeeting zone 310B using a real-time messaging service (RTMS) 1410. Inone embodiment of the present invention, RTMS 1410 is implemented usingthe well-known TCP/IP communications protocol. In some alternateembodiments, the WebEx Transport Protocol, discussed above, is used.

CB server 380C, in turn, connects to client computer 210B via its ownARM server 1240 and TP server 1250 (not shown)

FIG. 15 is a flow diagram of operation 1500 for transmitting data fromclient computer 210A to client computer 210B using distributedcollaborative computer system 300 (FIG. 3). First, CB server 380Bestablishes a link to CB server 380C using real-time messaging service1410 (stage 1510, as illustrated in FIG. 14). The session information isthen replicated from CB server 380B to CB server 380C (stage 1520). Datarouted from client computer 210A is then transmitted from CB server 380Bto CB server 380C over real-time messaging service 1410 (stage 1530).The data received by CB server 380C is then routed to client computer210B using TP server 1250 (stage 1546). Stage 1550 then determines ifadditional data needs to be transmitted from client computers 210A and21B, in which case stages 1530-1550 are repeated. Otherwise, operation1500 terminates.

Distributed collaborative computer system 300 allows users of clientcomputers 210 n to participate in on-line conferences by sharing bothaudio and video signals. In particular, distributed collaborativecomputer system 300 allows users to share images of a document that canbe marked-up by conference participants (document viewing). Documentviewing is described in further detail in U.S. Pat. No. 5,577,188“Method to Provide for Virtual Screen Overlay” and co-pending andcommonly-assigned U.S. patent application Ser. Nos. 09/471,938 and09/591,377(filed on Dec. 23, 1999 and Jun. 9, 2000, respectively), citedand incorporated above. In addition, users may share control of anapplication program executed on any of the client computers 210 nparticipating in the on-line conference (a process known as applicationsharing). Application sharing is described in further detail inco-pending and commonly-assigned U.S. patent application Ser. No.09/442,424 (filed Nov. 17, 1999), cited and incorporated above.

During document viewing, the presenter may choose to skip one or morepages in the document being viewed. FIGS. 16A and 16B are flow diagramillustrating the skip page operation 1600 used to control transmissionof pages between the presenter's client computer 210 n and otherparticipants' client computers 210 n.

First, an App server 390 n providing the document viewing application(also referred to as the docview server) assigns unique IDs to each pagein the document being viewed (stage 1605, FIG. 16A). The page IDs andpage content data are then passed to ARM client 1220 and from ARM client1220 to ARM server 1240 (stage 1610). ARM server 1240, in turn, beginstransmitting the document page IDs and data over a shared data queue onhigh-speed real-time messaging link 1420 (stage 1615). The first page IDis then sent to all client computers 210 n connected to the conference(stage 1620). Client computers 210 n, in turn, request the first pagedata from the shared data queue (stage 1625) and CB server 380 n sendsthe first page data to client computers 210 n (stage 1630). Stage 1635then determines whether the presenter has elected to jump to a new pagein the shared document, in which case operation 1600 proceeds to stage1640. Otherwise, operation 1600 proceeds to stage 1655. In stage 1640(FIG. 16B), the presenter's client computer 210 n broad casts the newpage ID to all client computers 210 n participating in the conference.The new page data is then transmitted over the shared data queue (stage1645) and client computers 210 n request the new page from the sharedmedia queue (stage 1650).

Alternatively, stage 1655 determines if all data transmitted on theshared data queue has been received, in which case the docview server isnotified (stage 1660. Otherwise, operation 1600 proceeds to stage 1635.

Stage 1665, in turn, determines whether the shared data queue is nolonger needed, in which case the shared data queue is emptied (stage1670) and operation 1600 terminates. Otherwise, operation 1600 proceedsto stage 1635.

FIG. 17 is a flow diagram of a client browser operation 1700, inaccordance with some embodiments of the invention. First, client browser320 receives conference parameters from CB server 380 n (stage 1710).Client browser 320 then connects to CB server 380 n (stage 1720) toparticipate in the conference. Stage 1730 checks the status of CB server380 n. If a failure of CB server 380 n is detected, client browser 320attempts to reconnect to a new CB server 380 n (stage 1740) and stages1710-1730 are repeated. Otherwise, client browser 320 continues tomonitor the status of CB server 380 n.

FIGS. 18A, 18B, 18C1-3, 19A, 19B, 20A, 20B and 20C are views of webpages displayed by client browser 320 (FIG. 3) during operation ofdistributed collaborative computer system 300.

Meeting center web page 1800 (FIGS. 18A, 18B and 18C1-3) is displayedwhen a user first accesses web server 335 (FIG. 3) through clientbrowser 320. Meeting center web page 1800 contains a list of current andscheduled meetings the user may want to join. In addition, the user maycreate a new meeting by selecting create meeting button 1810, causing asign in prompt to be displayed in meeting center web page 1800 (FIG.18B). If the user is not already registered with the service, the usercan register by selecting new user link 1820. Otherwise, the user canenter ID and password information in login prompt 1830. If the user'sdata is successfully authenticated with the information stored in webdatabase 337 and/or central operation database 340 (FIG. 3), a createnew meeting prompt 1840 is displayed in meeting center web page 1800(FIGS. 18C1-3). The user can then enter meeting parameters such as date,time, and attendee list by filling in new meeting prompt 1840. The usercan also edit meeting options by selecting edit options button 1850,thereby causing meeting options web page 1900 (FIGS. 19A-19B) to bedisplayed. Once the user has entered the desired meeting information onmeeting center web page 1800, the user can either schedule the meetingby pressing schedule button 1860 or start the meeting by pressing startnow button 1870.

Meeting options web page 1900 allows the user to set specific meetingoptions such as features, client type, frequency and reminders. Once theuser is satisfied with the selected options, the user can return tomeeting center web page 1800 by pressing submit button 1910.

Meeting web page 2000 (FIGS. 20A-20C) is displayed to the user during ameeting. Meeting web page 2000 includes a shared pane 2010, an attendeepane 2020 and a message pane 2030. Information shared among meetingparticipants are displayed in shared pane 2010. The user can shareimages, documents, applications, web pages, desktops and whiteboards byselecting an appropriate entry from tools menu 2040 (FIG. 20B). Forexample, if the user selects to share an image to be marked up by themeeting participants, the image is displayed in shared pane 2010 (FIG.20C). One or more users can then mark up the image by selecting adrawing tool from drawing menu 2050 and drawing over the image. Attendeepane 2020 contains a list of meeting attendees. Alternatively, attendeepane 2020 can used to display polls taken among the meeting attendees ora video conferencing images. Finally, message pane 2030 can used tocompose, send and receive messages among two or more meeting attendees.

Since conference information is replicated across all CB servers 380 nhandling the conference and can be reconstructed by meeting manager 350,failure of one or more CB servers 380 n does not disrupt the conferenceand can be gracefully recovered. As a result, the distributedcollaborative computing system of the present invention eliminates thesingle point of failure limitation of prior art collaborative computingsystems. In addition, since multiple server computers 220 n are used tohandle an on-line conference, the distributed collaborative computingsystem of the present invention may handle conferences with an arbitrarynumber of participants, without any limitations imposed by theprocessing capacity of any single server computer. By contrast, priorart systems were limited to conferences whose participants could all behandled by a single server computer.

Alternate Embodiments

The order in which the steps of the present method are performed ispurely illustrative in nature. In fact, the steps can be performed inany order or in parallel, unless otherwise indicated by the presentdisclosure.

The method of the present invention may be performed in either hardware,software, or any combination thereof, as those terms are currently knownin the art. In particular, the present method may be carried out bysoftware, firmware, or microcode operating on a computer or computers ofany type. Additionally, software embodying the present invention maycomprise computer instructions in any form (e.g., source code, objectcode, interpreted code, etc.) stored in any computer-readable medium(e.g., ROM, RAM, magnetic media, punched tape or card, compact disc (CD)in any form, DVD, etc.). Furthermore, such software may also be in theform of a computer data signal embodied in a carrier wave, such as thatfound within the well-known Web pages transferred among computersconnected to the Internet. Accordingly, the present invention is notlimited to any particular platform, unless specifically stated otherwisein the present disclosure.

While particular embodiments of the present invention have been shownand described, it will be apparent to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspect and, therefore, the appended claims areto encompass within their scope all such changes and modifications asfall within the true spirit of this invention. Volume in drive D is001227_0945 Volume Serial Number is F65F-BB64 Directory of D:\ Dec. 27,2000 09:46a <DIR> Dec. 27, 2000 09:46a <DIR> Dec. 18, 2000 05:46p 25,012ATPROC-1.CPP Dec. 18, 2000 05:46p 3,230 ATPROC-1.H Dec. 18, 2000 05:46p9,645 PMSPACKT.H Dec. 18, 2000 05:46p 9,312 PSPACKT.H 6 File(s) 47,199bytes 0 bytes free

1. A method of distributed collaborative computing comprising:partitioning a collaboration function into sub-functions; assigning atleast one said sub-function to each of a plurality of logical processes;associating a respective management process with each of said pluralityof logical processes, said logical processes configured so that eachsaid logical process is capable of communicating with every other saidlogical process thru said respective management process; communicatingbetween said logical processes using said respective managementprocesses; and monitoring said respective management processes with asingle supervisor process; wherein said communicating employs a secureprotocol on a dedicated network.
 2. The method of claim 1, wherein saidsecure protocol comprises encryption.
 3. The method of claim 1, whereinsaid secure protocol comprises compression.
 4. The method of claim 1,wherein said secure protocol comprises TCP/IP messages employing aproprietary message syntax.
 5. The method of claim 1, wherein saidsecure protocol comprises a proprietary message syntax, compression, andencryption.
 6. A computer program for use in distributed collaborativecomputing, comprising computer instructions for: partitioning acollaboration function into sub-functions; assigning at least one saidsub-function to each of a plurality of logical processes; associating arespective management process with each of said plurality of logicalprocesses, said logical processes configured so that each said logicalprocess is capable of communicating with every other said logicalprocess thru said respective management process; communicating betweensaid logical processes using said respective management processes; andmonitoring said respective management processes with a single supervisorprocess; wherein said communicating employs a secure protocol on adedicated network.
 7. The computer program of claim 6, wherein saidsecure protocol comprises encryption.
 8. The computer program of claim6, wherein said secure protocol comprises compression.
 9. The computerprogram of claim 6, wherein said secure protocol comprises TCP/IPmessages employing a proprietary message syntax.
 10. The computerprogram of claim 6, wherein said secure protocol comprises a proprietarymessage syntax, compression, and encryption.
 11. A computer-readablemedium storing a computer program executable by a plurality of servercomputers, the computer program comprising computer instructions for:partitioning a collaboration function into sub-functions; assigning atleast one said sub-function to each of a plurality of logical processes;associating a respective management process with each of said pluralityof logical processes, said logical processes configured so that eachsaid logical process is capable of communicating with every other saidlogical process thru said respective management process; communicatingbetween said logical processes using said respective managementprocesses; and monitoring said respective management processes with asingle supervisor process; wherein said communicating employs a secureprotocol on a dedicated network.
 12. The computer-readable medium ofclaim 11, wherein said secure protocol comprises encryption.
 13. Thecomputer-readable medium of claim 11, wherein said secure protocolcomprises compression.
 14. The computer-readable medium of claim 11,wherein said secure protocol comprises TCP/IP-messages employing aproprietary message syntax.
 15. The computer-readable medium of claim11, wherein said secure protocol comprises a proprietary message syntax,compression, and encryption.
 16. A computer data signal embodied in acarrier wave, comprising computer instructions for: partitioning acollaboration function into sub-functions; assigning at least one saidsub-function to each of a plurality of logical processes; associating arespective management process with each of said plurality of logicalprocesses, said logical processes configured so that each said logicalprocess is capable of communicating with every other said logicalprocess thru said respective management process; communicating betweensaid logical processes using said respective management processes; andmonitoring said respective management processes with a single supervisorprocess; wherein said communicating employs a secure protocol on adedicated network.
 17. The computer data signal of claim 16, whereinsaid secure protocol comprises encryption.
 18. The computer data signalof claim 16, wherein said secure protocol comprises compression.
 19. Thecomputer data signal of claim 16, wherein said secure protocol comprisesTCP/IP messages employing a proprietary message syntax.
 20. The computerdata signal of claim 16, wherein said secure protocol comprises aproprietary message syntax, compression, and encryption.